1. Field of the Invention
The present invention relates to a process arid apparatus which can be utilized for the design of for example a digital filter and which give a suiting function that may be used for such a design.
2. Description of the Related Art
For example, in the design of a conventional digital filter, the practice has been to approximate a curve expressing the amplitude characteristic of the filter by the optimization method and to calculate a transfer function based on that approximated curve. As one example of the optimization method, there has been known a method in which a sequence of points expressing an ideal characteristic is prepared, a function including a plurality of parameters for approximating this is set up, a distance between this function and the sequence of points is sought, and the parameters are determined to give the minimum sum of the square of this distance, whereby a desired approximated curve is obtained.
However, this conventional technique expresses the input data as a set sequence of points with no margin of error and merely calculates the distance between this input data and a target function. Where the input data has a certain degree of spread due to error etc., it has not been able to handle that spread.